How can I optimize my Time Machine WIFI network?

Any wireless that does a double hop is to be avoided..

In this case if both your Apple TV and your device that you want to share the screen are wirelessly connected.. things can go very very slow. This is double hop.. first hop device to the airport.. second hop airport to the apple TV. Packets travel very slowly across this connection. If at all possible plug the Apple TV into the airport by ethernet .. the improvement will be out of this world.

If that is not possible.. it might be worth investing in another airport to use close to the TV. See list below of info I need to help you with that.. it doesn't mean a new Time Capsule.. or Extreme.. an older Gen5 AE can be excellent for this job.

It can help to force connections to the fastest speed wireless.. Apple airports (all the current ones) are dual band.. 2.4ghz is slow but long range.. 5ghz is fast but short range. If you connect to the airport on 2.4ghz due to signal it can still be faster to connect to 5ghz.. to do that you need to use different names for each band.

To give you a better idea of what to do I need more info.

Where is your Time Capsule located in relation to the appleTV and device?

Is it possible to plug by ethernet either or both devices?

What model is your Time Capsule?

(Time Machine btw, is software for backup on your computer.. the router is called Time Capsule.. common mistake).

The normal settings for your Time Capsule wireless are already optimized for best performance, so unless you have changed some settings around, there is not much that you can do to improve performance....unless....you want to start over again and reset the Time Capsule back to default settings and then set it up again to see if will help the wireless.

Sometimes, it will help to assign separate names to the 2.4 GHz and 5 GHz signals, but I've not seen much improvement when I've tried this in the past.

Resetting the Time Capsule back to default settings and then setting it up again is something that you should do whenever you make a major change on a network, like changing the modem, or changing your Internet Service Provider. However, sometimes you can get away with not doing this.

If the Time Capsule seems to be working OK with your other devices, my recommendation would be to reset the Apple TV back to its original default settings and then set it up again. Once the Apple TV has been reset back to default settings, temporarily move the Apple TV close to the Time Capsule to set it up again.

Ideally, you would want to use a permanent wired Ethernet cable connection from the Time Capsule to the Apple TV, because that is always the fastest and most reliable type of connection to use.

If you cannot connect the Apple TV using a wired connection, keep in mind that any type of obstruction in the direct signal path between the Time Capsule and Apple TV will slow the wireless signal significantly, so you would want to have line-of-sight between the Time Capsule and Apple TV as much as possible.

If that is not possible, how far apart will the Time Capsule and Apple TV be located from each other?

How many obstructions.......walls, ceiling, heavy furniture, large mirrors, etc.....are there in the direct signal path between the Time Capsule and Apple TV?

Some forms of newer home construction use a type of wall and ceiling insulation that incorporates a metal foil backing on one or both sides of the insulating material.....and, as you already know.....not much of a wireless signal is going to make it through metal, so wireless can present a challenge as far as good performance is concerned.

I too have an AppleTV 4th Gen that I either AirPlay to or that I use Apps for. I know I ended those thoughts with a preposition. Sorry. On YouTube I have multiple problems with a lag or a blurry image in the videos. I have always assumed it was because that the user who uploaded the video had uploaded a video with problems. Because of information I have recently learned, I have begun to think it is something else that is causing this problem (blurry videos or terrible buffering or speech lags behind the video). I have an AirPort Time Capsule and an AirPort Express. The Express is close enough to the TV that I could use an ethernet to connect to it. Do you think that would solve the problem I am experiencing? I don't think my Express has a different name than the 5GHZ Time Capsule. How would I get the AppleTV to recognize the Express? Any ideas here would be much appreciated. I've been blaming YouTube for these problems. I told them their app had issues. They agreed. I don't have these problems if I view the videos within Safari on my iMac 21.5 with High Sierra 10.13.1. I've been either AirPlaying the videos from my iMac or I've been watching using the App on the AppleTV. I'm trying to manage entertainment without paying for the unconscionability high cost of cable.

Do you think that would solve the problem I am experiencing?

We still don't know enough about the problem that you are experiencing. Are you having the same kind of problem on other sites and other videos....or.....is it only this particular video that is presenting problems?

I don't have these problems if I view the videos within Safari on my iMac 21.5 with High Sierra 10.13.1. I've been either AirPlaying the videos from my iMac.....

Well, this tells you that the Apple TV is picking up a good signal from the Time Capsule and AirPort Express, so that is not likely the real issue here. In other words, if the Time Capsule, or Express, or Apple TV were not working reasonably well, you would experiences problems on any video that was streaming to the Apple TV.

As far a connecting the AirPort Express to the Apple TV using Ethernet, that will improve your chances of better performance.....but.....you still have a wireless connection between the Time Capsule and the AirPort Express, if I am understanding your setup correctly.

Trying to extend a network using wireless will always result in a loss of at least half of the potential performance on your network, so in order to make a really meaningful improvement, you would need to connect the Apple TV directly to the Time Capsule using Ethernet........or......connect the Time Capsule to the AirPort Express using Ethernet, and then connect from the AirPort Express to the Apple TV using Ethernet.

I have an AirPort Time Capsule and an AirPort Express.

From a streaming point of view this is BAD..

No wireless should go for more than one hop.. I am assuming the TC and the Express are not linked by ethernet.. please do so if that is possible.

The Express is close enough to the TV that I could use an ethernet to connect to it.

Do it.. do it now.. that is at least cutting one hop.. if you are using wireless from the source device.. that would mean three wireless hops and that aint ever gonna work.. (much worse than ending sentences with prepostion which is actually a rule from Latin!).

I would look carefully at signal strengths and link speeds.. none of this info comes to hand easily.. but the main point and Bob's post reiterates it.. use wired connection.. when it comes to streaming.. wifi is NOT GOOD.. = BAD.

For some people even using homeplug (powerline, Ethernet over Power adapters) will eliminate the problem.

Thanks for the info. I have some work to do now. I'm having to rethink my entire wireless setup.